<%@ page import="coe.pumbaa.Post" %>

          <fieldset>
            <label>Title</label>
            <g:textField name="title" required="" value="${postInstance?.title}"/>
          </fieldset>
          <fieldset>
            <label>Description<input type="button" id="addPic" class="btn_cam" onClick="addPicTag()"/></label>
            <textarea rows="12" name="description">${postInstance?.description}</textarea>
          </fieldset>
<script>

    function addPicTag() {
      document.postForm.description.value = document.postForm.description.value+'[img]url picture[/img]';
    }
  </script>